The invention relates to a device for decoupling a constant velocity joint from a drive shaft. The invention especially relates to a device, by which the constant velocity joints commonly used in power transmission of vehicles, can be decoupled from the drive shaft.
The constant velocity joint is mainly composed of an outer part, inner part, balls and ball holder. The outer part is attached to the hub of the wheel of the vehicle and the inner part to the drive shaft, which functions as a transmission shaft between the gearing and the wheel. The balls have been placed in the ball holder, which on the other hand is inside the outer part. Spaces, in which the balls can move, have been arranged in the ball holder and in the outer part, which enables bending of the joint when the wheel turns. The end of the inner part is often a splined shaft, which has been arranged in a similarly splined hole in the ball holder. The shaft is secured in its place with a retaining ring, which can be opened for example by pliers or which opens by axial force directed towards it. In order to dissemble the joint, a relatively strong axial force is often needed even after releasing the retaining ring. The joint has been protected against dirt with a protective rubber.
Changing a broken protective rubber, cleaning and checking of balls and ball holder and sliding surfaces are often sufficient maintenance measures for joints. In connection with the work, the holders of the protective rubber of the joints are detached and the protective rubber is pushed aside. The joint is usually dissembled by striking the outer part with a hammer and drift, with sliding hammer or with air hammer, while the inner part must simultaneously be kept stationary. Often also a joint equipped with a safety ring that can be opened with needle-nose pliers must be dissembled by striking, because the grip of the pliers can be unstable due to damages in the secure ring or because the secure ring is slippery of lubricating grease. In order to cut down the costs it would be preferable to perform the maintenance work of the joint without detaching the drive shaft completely from the vehicle. In the commonly used striking method the drive shaft must be completely detached from the driving gear, because there is not enough room for striking when the shaft is in its position. It is difficult to arrange the outer part so that it stays in position, which makes it possible that the drive shaft is accidentally detached from the driving gear and the transmission oil leaks out. The force needed for striking can be excessive, because the retaining ring can be damaged as a result of stress during driving or because the groove of the hub and the shaft have been stuck. The industrial safety of the striking method is inadequate, and the working positions can be ergonomically unfavourable. The strikes can cause damage to the person performing the work, to the parts in the vicinity of the joint, or to the joint itself. When using striking tools, the chips coming loose due to the force of the strikes can cause eye injuries, in particular. For example damage in the ball holder of the joint can occur unnoticed and a latent defect compromising the traffic safety is developed in the joint. Due to deficiencies and laboriousness of the current methods the entire drive shaft is replaced for example in professional repair shops, although often only the outer drive joint is broken. This causes the owner of the vehicle substantial additional costs.
Some of the above-mentioned problems are solved and some deficiencies of the known technique are removed with the present invention, and a device for decoupling a constant velocity joint from the drive shaft is achieved, which device is simple and reliable and has low costs. Said advantages are achieved by a device according to the invention, which is characteristic by what is defined in the protective claims.
The device of the invention is mainly composed of a frame fitted into a fixing thread on the outer part of the constant velocity joint and of arms connected to it. The arms reach past the drive joint and mainly transversal fastening elements for gripping the inner part of the drive joint have been attached to them. There are preferably two transversal fastening elements, which have been placed opposite each other. The elements are clamped to the inner part preferably on a spot where the fixing groove of the protective rubber is, in which groove the projections on the corresponding surfaces of the fastenings elements have been fitted in. For example screws which have been fitted to run through the holes in the ends of the transversal fastening elements can function as clamping elements. Concurrently, the screws run through the holes in the arms. By turning the nut in the fixing thread of the constant velocity joint, reverse axial forces are effected in the inner and the outer part, and they are thus detached from each other.
The invention enables detaching of the constant velocity joint from the drive shaft without phases of work involving strikes. The device speeds up changing of the joint and the protective rubber. In addition, the work can be performed while the drive shaft is in its position in the vehicle, which saves costs considerably. The axial force is effected by the own mounting nut of the constant velocity joint. The attaching parts belonging to the device effectively grip the inner part so that the joint remains straight during the detachment. The device can easily be fitted for drive shafts of different thickness and lengths. The device according to the present invention is simple and reliable and has low costs, which makes it economically possible to acquire it both for professional use and for household use as well as for hobby use.
The invention is explained in detail in the following by help of some preferred examples of the embodiments and by referring to the attached drawings.